1. Field of the Invention
This invention relates to a complex cutting-blade tool and to a machining method employing that complex cutting-blade tool, primarily for use in hole machining.
2. Description of the Related Art
When a through hole is formed in a piece of workpiece using a drill, burrs are produced at the exit of the through hole. It is also necessary in some cases to bevel both the entrance and exit of a through hole formed with the drill.
In Japanese Utility Model Application Laid-open No. 318149/1993 is disclosed art for using beveling and burr-removing cutting tools attached to a drill for removing the burrs from and beveling the exits of through holes opened with the drill and for beveling the entrances thereof. And in Japanese Utility Model Application Laid-open No. 63713/1993 is disclosed a cutting tool for beveling entrances and exits of through holes.
However, with the drills noted in the foregoing, the through hole exit burr removal and beveling process and the through hole entrance beveling process, done by causing the drill shank to revolve eccentrically about the machined hole, are separate processes. For that reason, the drill or tool is caused to revolve eccentrically about the machined hole to perform through hole exit burr removal and beveling, and then, subsequently, it is caused to revolve eccentrically about the machined hole to perform through hole entrance beveling. Thus, in order to perform beveling on the entrance side and beveling and burr removal on the exit side of one through hole, the same tool must perform the same movements twice, which requires a long time and is time-consuming.
Special tools for performing through hole entrance and exit beveling are disclosed in Japanese Patent Application Laid-open No. 24804/1980 and Japanese Patent Application Laid-open No. 14801/1986, but these tools can no longer be used once the height of the through hole (i.e. the thickness of the workpiece) has changed.